A shearing machine for steel material is widely used which is mounted as an attachment on a forward end of an arm of a working machine, such as a power shovel, in order to shear or cut steel material at a destruction site for scrap or waste items. Various types of shearing machines are known. Generally, such shearing machines include a body, and a pair of upper and lower jaws supported at the forward end portion of the body for open-close movement relative to one another. Each of the upper and lower jaws includes a shearing blade attached thereto. Depending upon a particular application of the shearing machine, the upper and lower jaws are supported by a common shaft (single-pivot type), or by separate two shafts (double-pivot type). In general, a single-pivot type is suitable for a shearing machine having a relatively shorter open-close stroke of jaws, while, a double-pivot type is suitable for a shearing machine having a relatively longer open-close stroke of jaws.
The body of the shearing machine is, in general, formed at the rearward end portion thereof with two holes for pin connection. A first connection pin is inserted through one of the holes in the shearing machine body and a hole for pin connection in the forward end of the arm of the working machine. A second connection pin is inserted through the other hole in the shearing machine body and a hole for pin connection in the forward end of a piston rod of an arm cylinder of the working machine (depending upon a particular case, a link rod may be used). Thus, the shearing machine body may be pivoted in the vertical direction upon contraction or extension of the arm cylinder.
Depending upon the particular type of the shearing machine, one or two cylinders are disposed on the shearing machine body. The cylinder(s) cause vertical, open-close movement of the upper and lower jaws. When one cylinder is used, the forward end of the piston rod and the upper jaw are directly connected. Thus, the lower jaw functions as a stationary jaw. Then two cylinders are used, the forward end of each of the piston rods is directly connected to a respective one of the upper and lower jaws.
In a conventional shearing machine of a single-pivot, two-cylinder type, the cylinders are arranged in a vertical orientation. That is to say, the two cylinders are disposed at vertically opposite sides of the shearing machine body, so that they protrude vertically from the shearing machine body in an aligned manner along a line in a plane extending in the open-close direction of the upper and lower jaws, i.e., in the direction in which shearing action of the shearing machine proceeds.
In the shearing machine of a single-pivot type mentioned above, a relatively shorter distance is defined between the upper and lower jaws, so that the shearing machine, per se, is thin in the vertical direction. It is noted, however, that the two cylinders are so disposed as to protrude from the shearing machine body in the vertical direction. Such cylinders obstruct an operator to view the shearing blades from an operator's seat. Depending upon the position of the shearing machine, it is, therefore, difficult for the operator to view the shearing action of the shearing machine.
The shearing machine of a single-pivot type is advantageous in that it has a shorter open-close stroke of the jaws. To the contrary, such advantage might constitute some disadvantage. That is to say, when steel material is clamped between the shearing blades of the upper and lower jaw having a shorter open-close stroke, the shearing blades represent a widely opened configuration being divergent toward the forward ends of the shearing blades. Thus, it is possible for the steel material to be slipped toward the forward ends of the shearing blades as the upper and lower jaws are closed.